Sphincter muscles are generally circular, ring-shaped muscles that can contract to close off a body passage or opening. Sphincter muscles are located in many parts of the body, including locations associated with the esophagus, epiglottis, stomach, urethra, upper intestine, lower intestine, anus, and bladder, among others. A sphincter muscle typically surrounds a portion of tissue comprising a passage or opening of the body, such as a canal or tract, and controls passage of bodily fluids by contracting. Passage of bodily fluids into or out of the associated passages and openings cannot be sufficiently controlled if the sphincter muscle suffers from dysfunction or damage. For example, fecal incontinence can result from problems with the anal sphincter. The anal sphincter can become weakened or damaged from rectal prolapse or, in women, during childbirth. Urinary incontinence can result from problems with the sphincter muscles associated with the bladder or urethra. Dysfunction of other sphincter muscles can result in similar incontinent conditions or difficulties with bodily functions.
Medications, dietary changes, biodfeedback, and similar treatments may be insufficient to correct a dysfunctional sphincter muscle. In those situations, surgery might be necessary to repair the sphincter muscle and restore normal functioning. Surgery for repair of a sphincter muscle typically involves external sphincteroplasty, a shortening of the sphincter to ensure that it can properly close off its associated body passage or opening. The sphincter has an axial length, along the axis of the associated passage or opening, and has a circumferential length. Currently, surgery to repair a sphincter muscle begins with incisions to expose the muscle itself, followed by shortening the circumferential length of the sphincter muscle by the surgeon manually grabbing hold of the muscle and cutting or opening the sphincter muscle, removing a circumferential segment of the sphincter, and then re-joining the cut ends with a suture or staple.
The extent of muscle shortening from the surgery can be difficult to determine, because the muscle is in a non-functioning condition from being surgically exposed. Post-operative treatment requires careful control of infection risk at the wound site surrounding the sphincter muscle. Unfortunately, some such sphincteroplasty procedures are not especially effective. Some ineffectiveness can be the result of, for example, the difficulty of determining the extent of muscle shortening from the surgical procedure.
Making incisions and exposing the sphincter muscle is a relatively invasive procedure that requires care and attention to operating resources and surgical procedures, control of infection, and post-operative recovery treatment. A less invasive treatment for sphincter dysfunction could save costs, reduce the risks of surgery, provide efficacious results, and be better tolerated by patients. There is a need for treatment of dysfunctional sphincter muscles that meets these requirements.